As an alternative power device material to a Si semiconductor, a SiC (silicon carbide) semiconductor which can realize higher withstanding voltage, higher current, lower ON resistance and the like than a Si semiconductor has become the focus of attention in recent years (see Patent Document 1, for example).
A SiC power device is utilized as a switching element of various kinds of inverter circuits to be incorporated in, for example, a motor control system, an electricity exchange system or the like.
When a SiC power device (a switching element) in a motor control circuit or the like is turned off to interrupt electric current flowing through a motor coil, electromagnetic induction of the motor coil causes a diode to consume counter electromotive force generated in the motor coil.
In particular, application of high counter electromotive force to a switching element is prevented by causing electric current generated due to the counter electromotive force to flow to a motor coil as reflux current, by virtue of rectification of a parasitic diode (a body diode) by p-n junction between a p-type channel region and an n-type drain region existing in a device.